Analyzer prism



. Enamel-Aus ANALYZER PRIsu Filed Aus. 29. 1921 Fig.l 4l4 Fig/Ir lFatentedr'eb. Z4, 1925.

UNITED STATES PATENT GFFICE.

ARTHUR EHRINGHAUS, OF GOTTINGEN, GERMANY, ASSIGNOR T THE FIRM 0F B.WINKEL G. M. B. H., 0F GOTTINGEN, GERMANY.

-- ANALYZER PRISM.

Application led August 29, 1921.

T o all whom it may concern.'

Be it known that I, ARTHUR EHRINGHAUS,

a citizen of the German Empire, and residing at Gottingen, Germany, haveinvented a new and useful Analyzer Prism (for which I have filed anapplication in Germany, April 7, 1920), of which the following 1s aspecification.

The present invention relates to an analyzer prism which is designed fora tube-analyzer for microscopes. either for observation or forphotograhpic or projection work. In order to obviate, whilst using atube-analyzer, the troubles, which with the use of an ordinary analyzerprism are caused by the astigmatism resulting from the same, it has beensuggested in the German Patent Specification 296,000 (in the event ofthe orthoscopic use) to dispose in front of the prism a. dispersive lenswhich renders the ray pencils, emanating from the differentobject-points and converging behind the microscope objective, parallel,and to dispose behind the pism a collective lens imparting again theoriginal convergence to the ray pencils emerging parallel from theprism. The addition of two such lenses to the analyzer prism has thedrawback that the analyzer then consisting of the prism and the twolenses cannot owing to the increase of its length. as a rule, be broughtthrough the same lateral opening of the microscope tube into the latterwhich opening was hitherto suiicient for introducing the mere prism.

According to the invention the length can frequently be limited alreadyin a suicient way without impairing the optical effect, by dispensingwith one of the two lenses and by attaining their effect by means of sodevising the respective end-surface of the prism as to be dispersive orcollective, according to the necessity of replacing the dispersive orthe collective lens. In that case the respective surface may be aspherical surface or another surface of rotation (having thelongitudinal axis of the prism as an axis of rotation).

The shortest length, viz, a length equal to that of the single prism, isobtained by also dispensing with the other lens and by devising therespective end-surface of the rism 1n such a way that it replaces thisens; hence this other end-surface becomes Serial No. 496,733.

collective, if the first-mentioned one be dispersive, and vice versa.

For couoscopic use the path of rays is influenced just in the oppositemanner: it has accordingly been suggested in the German PatentSpecification 315149 to dispose in front of the analyzer prism acollective lens and behind the prism a dispersive lens. According to theinvention the analyzer prism can also be constructed for this kind ofuse. In that case it is always necessary to provide at the front end ofthe prism for a collective effect in order to allow the pencil, emergingfrom the rear focal point of the microscope objective, of entering theprism by parallel rays. At the rear end it is necessary to provide for adispersive effeet if the pencil. emerged from the prism, is to be givenagain the original divergence. In that case the same Amici-Bertrand lensis to be used at the back which` with the use of an ordinary analyzerprism, is destined to make the rays forming the aforesaid pencilintersect each other in the front focal plane of the microscope-ocular.If only one Amici-Bertrand lens of inferior refractive power is to beused. the rear endsurface of the prism is to be given a correspondinglyslighter dispersive effect. lVith a certain refractive power of theAmici-Bertrand lens it is necessary to give the rear end-surface of theprism the refractive power zero. i. e. to leave the surface plane: inthe event of a still inferior refractice power of the lens theend-surface is even to be given a collective effect. and. finally. thelens may even be dispensed with entirely by giving the rear end-sur faceof the prism a sutliciently powerful collective effect.

In the annexed drawing the invention is illustrated by severalconstructional examples. Figs. 1 to 3 relate to the orthoscopic path ofrays; Fig. 1 shows a prism with dispersive front surface and plane rearsurface, Fig. 2 a prism with plane front surface and collective rearsurface, Fig. 3 a prism with dispersive front surface and collectiverear surface. Figs. 4 to 7 relate to the conoscopic path of rays; Fig. 4shows a prism with collective front surface and plane rearsurfaceJ Fig.5 a prismwith plane front surface and dispersive rear surface, Fig. 6 aprism with collective front surface and plane rear surface, Fig. 7 a

prism with collective front surface and collective rear surface.

Fig. 1 shows an example for orthoscopic use. .ln analyzer prism al isprovided at its front end-surface with al dispersive cavity bl; behindthe prism there is a collective lens cl. The plane of the object to beexamined is denoted b v XX; the microscope objective consists of thelenses d and c, the (Huggenian) ocular of the lenses and g. Thedispersive etl'ect of the cavity bl is so chosen that the convergentpencil of rays thrown upon the front end-surface of the prism penetratesthe prism by parallel rays; the collective effect of the lens cl is sochosen that the original convergence is restored again..

Fig. 2 shows as a substitute for the prism al along with the lens 0l ofFig. l a prism al, in front of which a dispersive lens b2 is disposedand the rear end-surface of which c2 is so devised as to be collective.

Fig. 3 shows as a substitute for the prism al along with the lens cl ofFig. l a prism a3, which has at its front end-surface a dispersivecavity bl and the rear end-surface c2 of which is so devised as to becollective.

Fig. 4 shows an example for conoscopic use. An analyzer prism lil is sodevised as to be collective at its front end-surface il; behind theprism a dispersive lens jl is disposed. The plane of the object to beexamined is again denoted by XX, and the lenses d, e, f and g correspondto those of Fig. l. A lens kl (Amici-Bertrand) disposed behind the lensjl serves for bringing about in the front focal plane of the ocular animage of the interference-image arising in the rear focal plane of theobjective.

Fig. 5 shows as a substitute for the prism hl as well as the lenses jland Isl of Fig. l a prism h2, the front end-surface of which is plane,in front of which a collective lens il is disposed, the rear end-surfacej2 of which is so devised as to be dispersive and behind which acollective lens lo is disposed, the refractive power of which is aboutequal to that of the lens kl.

Fig. 6 shows as a substitute for the prism hl as well as the lenses jland cl of Fig. 4 a prism hl agreeing with the prism kl of Fig. l as wellas a collective lens k3 disposed behind this prism, which lens is lesspowerful than the lens cl.

Fig. 7 shows as a substitute for the prism /f-l as well as the lenses jland icl a prism h3, the front end-surface z'l and the rear endsurface j3of which are so devised as to be collective.

I claim:

l. Analyzer prism for microscopes, one end-surface of this prism being acurved surface which is formed by a surface of rotation, the axis of thelatter coinciding with the longitudinal axis of the prism.

2. Analyzer prism for microscopes, both end-surfaces of which are curvedsurfaces which are formed each by a surface of rotation, the axis of thelatter coinciding with the longitudinal axis of theprism.

3. Analyzer prism for microscopes, one end-surface of this prism being aconcave surface of rotation, the axis of the latter coinciding with thelongtiudinal axis of the l ARTHUR EHRINGHAUS.

